Method and apparatus for pyrolytic decomposition of trash

ABSTRACT

INDUSTIRAL AND MUNICIPAL TRASH IS FED INTO ONE END OF A ROTATABLY SUPPORTED,ELONGATED DRUM, WHICH TURNS AT A RELTAIVELY SLOW RATE OF ROTATION AND THE CARBONIZED RESIDUE IS DISCHARGED FROM THE OTHER END. TRAPDOOR ARRANGEMENTS AT THE ENTRANCE AND EXITS ENDS ALLOW MATERIAL TO BE FED INTO AND DISCHARGE FROM THE DRUM AS THE LATTER REVOLVES, WITHOUT OPENING THE INTERIOR OF THE DRUM TO THE ATMOSPHERE. INTERNAL GAS BURNERS AT ONE END OF THE DRUM ARE OPERATED AT THE START OF OPERATIONS TO HEAT UP THE DRUM AND CONTENTS TO HIGH TEMPERATURE,CAUSING DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIAL WITH RESULTANT PRODUCTION OF COMBUSTIBLE GAS. FUEL SUPPLY TO THE BURNERS IS THEN CUT OFF AND AIR IS ADMITTED THROUGH BURNERS AT A CONTROLLED RATE TO MAINTAIN COMBUSTION OF GASES WITHIN THE INTERIOR OF THE DRUM TO THE EXTEND REQUIRED GAS IS EXOPERATING TEMPERATURES. EXCESS UNBURNED GAS IS EXHAUSTED AND COOLED, AND VOLATILE LIQUIDS ARE CONDENSED OUT.

' Sept. 24, 1974 R. I. BUCHVBINDER T AL -3,81 '38;015

METHOD AND APPARATUS FOR ,PYROLYTIC DECOMPOSITION or 'mxsn OriginalFiled Sent. 17} 1970 v 5 Sheets-She t 1 EXHAU T BLOWER w AIRH BLOWERFUEL VALVE REGULATING v MEANS YREGULATING MOTOR AIR LOCK CHAMBERINii/ENIORS 1908597 I EQZHEZ/VDEQ A1552 J fllCI/B/NQFQ "AGENT" p 24, 1 IR. I.IBUCHBIN DER EH1. 3,838,015

METHOD Am APPARATUS Fon- PYROLY'I'iC DECOMPOSITION OF TRASH Origiha1 F iledsent. 17, 1970 I I ,ishee'tis-sheet'g AIR LOCK EXIT CHAMBER 24, 1974R. BUCHBINDER ET AL 3,333,015?

METHOD AND APPARATUS FOR PYROLYTIC DECOMPOSITION 0F TRASHOriginal'F'iled Sent. 17, 1970 3 Sheets-$heet 5' INVENTORS 205527 Baas5mm? United States Patent 01 lice METHOD AND APPARATUS FOR PYROLYTICDECOMPOSITION OF TRASH Robert I. Buchbinder and Albert J. Buchbinder,West Covina, Califi, assignors to Devco Management Inc., New York, N.Y.Continuation of abandoned application Ser. No. 73,116, ,Sept. 17, 1970.This application Sept. 20, 1972, Ser.

Int. Cl. Cb 49/06, 53/00 U.s. Cl. 2019-1 16 Claims ABSTRACT OF THEDISCLOSURE Industrial and municipal trash is fed into one end of arotatably supported, elongated drum, which turns at a relatively slowrate of rotation, and the carbonized residue is discharged from theother end. Trapdoor arrangements "at the entrance and exit ends allowmaterial to be fed into and discharged from the drum as the latterrevolves,

-without opening the interior of the drum to the at- This is acontinuation application of application Ser. No. 73,116, filed Sept. 17,1970, and now abandoned.

BACKGROUND OF THE INVENTION The present invention pertains to apparatusfor the pyrolytic decomposition of the organic or combustible materialin municipal and industrial trash, so as to reduce the same to a charredresidue having only about 10-20% of its original bulk. At the same time,the combustible gas generated by the apparatus is utilized to maintainthe "elevated'temperatures required, thus making the pyrolytic processsubstantially self-sustaining.

The tremendous bulk of municipal and industrial trash that is generateddaily in our larger cities makes it es- "sential that some eifective andeconomical means be found for disposing of the same without pollutingthe atmosphere or otherwise producing offensive discharges.

In order to reduce the bulk of such trash, it has long been the practiceto'burn the trash at the city dump. This results in the creation of apall of oflensive, odorous smoke,

and such openburning is now prohibited by law in most parts of thecountry. Other methods of disposing of trash "are by incineration andsanitary landfill. Incineration has the serious problem of airpollution, which is extremely expensive to overcome. Sanitary landfillbecomes increasingly more diflicult as a municipality grows larger,

because of the unavailability of land near the population centers.

To eliminate the smoke problem, it has heretofore been proposed to burnthe trash in a rotating drum, or retort, which is heated by externalburners, so that the trash contained within the drum is reduced to charby destructive distillation, while combustible gas generated by theprocess is drawn off by blowers and mixed with the fuel gas and oxygengoing to the said burners, to provide fuel for the latter. The chiefdisadvantage of this arrangement is that with the burners on the outsideof the druin and the trash on the inside thereof, it is necessary thatall of the heat generated by the burners be conducted Patented Sept. 24,1974 through the walls of the drum, or retort, which results in rapiddeterioriation of the drum walls due to prolonged exposure to very hightemperatures. Using steel in the drum construction, it is necessary tolimit temperatures to 1000 F. or less, as the structural strength of thesteel is adversely affected by temperatures in excess of 1000 F. In suchprior apparatus, it is not possible to line the interior of the retortwith refractory material, as this would act as a heat barrier, and wouldprevent transmission of the heat by conduction from the external flameto the material contained within the retort. The relatively lowoperating temperature (i.e., less than 1000" F.) inside the drum has hadthe effect of reducing the rate-offlow capacity of such devices to aninefiicient level.

SUMMARY OF THE INVENTION The primary object of the present invention isto provide a new and improved apparatus for the pyrolytic decompositionof municipal and/or industrial trash to re-' duce the organic andcombustible content of the same to a charred residue, without producingobjectionable smoke or odors or other environment pollutant discharge.The charred residue, reduced to only 10 to 20% of its original bulk andnow completely inorganic and biologically stable, can be disposed of bycut-and-fill operations or by dumping at sea, as the case may be.

Another object of the invention is to provide an apparatus of the classdescribed which is thermally selfsustaining, after being brought up tooperating temperature, by using the combustible gas produced bydestructive distillation of carbonaceous material in the trash togenerate the heat necessary to sustain the pyrolytic process.

A further object of the invention is to provide a trashreducingapparatus in which the combusion takes place within the retort, insteadof externally thereof. The primary advantage of this feature is that itpermits lining the interior of the retort with refractory material sothat the steel walls of the drum are protected from the high temperatureflame and therefore are kept from being heated to such high temperaturesas to affect the strength of the steel, while at the same time, theoperating temperature within the restort is raised several hundreddegrees higher than the 1000 F. maximum that has heretofore beenallowable, with corresponding increase in efiiciency and rate flows.

These and other objects and advantages of the invention will becomeapparent to those skilled in the art upon consideration of the followingdetailed description of the preferred embodiment thereof, with referenceto the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of anapparatus embodying the principles of the invention;

FIG. 2 is a cut-away, fragmentary view of the inlet end of the apparatusshown in FIG. 1;

FIG. 3 is a view similar to FIG. 2, showing the drum revolved through180" from the position of FIG. 2;

FIG. 4 is a sectional view, drawn to somewhat larger scale, taken at 44in FIG. 1;

FIG. 5 is a sectional view, also drawn to a larger scale, taken at 5-.5in FIG. 1;

FIG. 6 is a view similar to FIG. 5, showing the drum turned from theposition of FIG. 5;

FIG. 7 is an enlarged sectional view taken at 7-7 in FIG. 1;

FIG. 8 is a View similar to FIG. 7, but showing the drum turned throughan angle of about from the position of FIG. 7; and

FIG. 9 is a sectional view taken at 9-9 in FIG. 1.

3 a 7 DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings, thedevice of the invention is designated in its entirety by the referencenumeral 10 and comprises an elongated, cylindrical drum 12, preferablymade of steel plate, which is supported for rotation about anapproximately horizontal axis. The drum 12 has an entrance end 14, anexit end 16, and an intermediate section 18 in which pyrolyticdecomposition of the trash takes place.

Fixed to the outside of the drum and encircling the same near each endthereof are circular steel tires 20, each of which rests on a pair ofhorizontally spaced-apart wheels 22 and 22 (FIGS. 1 and 4) which arerotatably mounted on suitable supporting structures. Wheels 22 haveradial flanges at each end which pass on opposite sides of theirrespective tire 20 to restrain the latter and that end of the drum, aswell, against endwise movement. Wheels 22, however, are straight-sided,cylindrical rollers that allow their tire 20 to slide endwise over themas the drum expands and contracts in length from heating and cooling.

Also fixed to the outside of the drum 12 and extending around thecircumference thereof is a ring gear 24, which has a small pinion 26meshed therewith. Pinion 26 is driven by motor 28 through a speedreduction gear box 30. The drum 12 is normally driven at a speed ofabout 3 revolutions per minute.

At the entrance end of the drum is a feed hopper 32, the bottom end ofwhich opens through a circular opening 34 in the end wall 36 of thedrum. Spiral flights 37 (FIG. 4) are attached to the inner surface ofthe drum just inside the end wall 36, and these serve to pick up thematerial and move it endwise along the drum in the direction away fromthe feed hopper 32 and toward the pyrolyzing section 18. Fixed to theinside of the drum 12 beyond the ends of the spiral conveyor flights 37,and completely spanning the interior thereof, are two bulkheads 33 and40, which are arranged at an angle to one another, as best shown inFIGS. 2 and 3. The first bulkhead 38 extends from a point just insidethe drum front end closure 36, and its plane forms an angle of about 30to the longitudinal axis of the drum. The second bulkhead 40 is shown atan angle of about 45 to the axis of the drum, and slopes in the oppositedirection. Bulkhead 38 has an opening 42 which is closed by a door 44that is hinged to the edge of opening 42 that is nearest the wall of thedrum. Thus, when the drum is turned to the position shown in FIG. 2, thedoor 44 drops open by gravity to the position shown, and trash containedwithin the entrance end of the drum is allowed to fall into a transferchamber 48 defined between bulkheads 38 and 40.

Bulkhead 40 has an opening 50 provided therein which is offset in theopposite direction from opening 42, so that it is substantiallydiametrically opposite from the latter with respect to the axis ofrotation of the drum. Opening 50 is closed by a door 52, which is hingedat 54 to that edge of the opening that is closest to the wall of thedrum. Thus, when the drum has turned 180 from the position shown in FIG.2, so that it has the position shown in FIG. 3, the door 52 drops openby gravity, and trash contained within the transfer compartment 48 isallowed to tumble out of the compartment into the midsection 18 of thedrum, where pyrolytic decomposition takes place.

In the midsection 18 of the drum are lifters (not shown) which may be inthe form of straight blades, or paddles, projecting radially inward fora short distance from the inner surface of the drum, and these pick upthe trash as the drum revolves and then drop it to the bottom, therebybreaking up the material and helping to preheat it uniformly throughoutits mass by cascading the material in the hot pyrolyzing section. Thelifters also help to movethe material endwise through the pyrolyzingsection and toward the exit end of the drum.

The exit end 16 of the drum is closed by a stationary end plate 56,which is sealed to the drum so that the latter can revolve with respectto the stationary end plate without allowing air to get into or out ofthe drum. Projecting into the interior of the drum through the end plate56 on opposite sides of center are two burner nozzles 58. These nozzlesare supplied with fuel 2 gas through a fuel pipe 60, and are alsosupplied with air for combustion of the gas by means of a blower 62,driven by a motor 64, the said blower deliveringits air to the nozzlesthrough pipes 66. A valve 68 in the fuel line 60 controls the flow offuel to the nozzles, while asecond, motor-actuated valve 70 in the airline 66 controls the flow of air to the burners. Valve 70 is controlledby a reversible electric motor 71. I

The burners 58 shoot long tongues of flame into the interior of the drum12, heating up the drum and its contents to a temperature of atleastapproximately 1100 F. During this initial heating stage, the supplyof oxygen admitted to the interior of the drum 12 is limited to the bareminimum required to support combustion of the fuel delivered to theburner nozzles 58, and as a result, the trash within the drum does notburn, but begins to undergo destructive distillation. By the time thetemperature of the interior of the drum has reached 1100 F, all of theoxygen that was initially contained within the drum has been used up andthe drum becomes filled with combustible gas produced by the destructivedistillation of the carbonaceous material in the trash. Upon reaching1100 F., the fuel supply is shut off, and oxygen is admitted in anamount just sufficient to support combustion of part of the combustiblegas within the drum. This combustion of the gas produced by thedistillation of trash produces enough heat to sustain the pyrolyticdecomposition of the trash without the necessity of supplying anyadditional fuel to the burner nozzles, and the process is thereafterself-sustaining as long as a continuous supply of trash is fed into thehopper 32 at'the entrance end of the drum.

As the drum continues to rotate, the material in the intermediatesection thereof works its way down toward the exit end 16, preferablyaided by gravity, which is made effective by mounting the drum with itsaxis at a very slight inclination to the horizontal.

Extending completely across the interior of the drum, near the exit end16 thereof, is a screen 72 of stainless steel or other heat-resistantmaterial, which functions to prevent any large pieces of non-combustiblematerial such as metal, glass, chunks of concrete or dirt, or the like,from passing down to the extreme end of the drum where the charredcombustible material is discharged. At. the same time, the flames fromthe burners 58, and burning gases released by the combustible materialin the pyrolyzing zone pass freely through the screen.

The large pieces of non-combustible material separated out by the screentrap 72 are discharged from the drum by the means shown in FIG. 5 and 6.In these two figures, the drum is seen to have two discharge chambers74, mounted on diametrically opposite sides of the drum. Each of thesechambers has an entrance door 76 and an exit door 78. Door 76 is hingedalong one edge at 80, while door 78 is hinged along one of its edges at82, to the trailing side of the chamber 74. In FIGS. 4-8, the drum isrotating in the counter-clockwise direction, as shown by the arrows. Thearrangement for the doors and their respective hinges is such that whenthe discharge chambers 74 are at the top of the drum, or at the lefthandside as viewed in FIGS. 5 and 6, both doors are held in place bygravity. As the discharge chamber reaches the bottom of the drum, door78 remains closed, but door 76 drops open, allowing the non-combustiblematerial within the drum to fall into the discharge chamber. As the drumcontinues to revolve, bringing the discharge chamber up to the positionon the right-hand side of the drum shown in FIG 6, exit door 78 opens,allowing material contained within the discharge chamber to drop out bygravity. Further rotation of the drum causes the door 78 to close. Thus,for any position of rotation of the drum, at least one of the doors 76,78 of each of the discharge chambers is closed, and the interior of thedrum is thereby closed to the atmosphere.

The charred material continues to work its way toward theexit end of thedrum, and passes through the screen 72. As the charred material reachesthe end of the drum, it is discharged through the arrangement shown inFIGS. 7 and 8.

Built out from the outer surface of the drum and extending continuouslyaround the circumference thereof is a discharge chamber 84. First andsecond discharge doors 86 and 88 are located on opposite sides of thedrum from one another. The first door 86 is associated with an opening91, which opens from the interior of the drum into the discharge chamber84, while the second door 88 is associated withan opening 89, whichopens from the discharge chamber 84 into the atmosphere. Door 86 ishinged to the drum at 90 on the leading edge of the opening 91, so thatit falls open by gravity when at the bottom of the drum (as in FIG. 7),and closes by gravity when at the top of the drum (as in FIG. 8). Door88 is-hinged to the outside of the discharge chamber at 92 on theleading edge of opening 89, so that it tends to fall open by gravitywhen at the bottom of the drum (as in FIG. 8), and tends to close bygravity when at the top of the drum (asinFIG. 7).

To keep the discharge door 88 from opening prematurely, means isprovided for holding the door closed until it reaches a particular pointin its rotational travel. Such means comprisesa pair of arcuatecam shoes94 and 95, which surround the lower section of the discharge chamber 84,asshown in FIGS. 7. and 8. The two cam shoes 94, 95 lie within a commonvertical plane perpendicular to the axis of the drum, and their:adjacent ends are spaced apart a short distance toform an opening 96,which is offset slightly to one sided a vertical line passing throughthe said axis. The cam shoes are spaced radially outward a .shortdistance from the. outer surface of the drum, to provide clearance forthe door 88 and its hinge 92' as the drum revolves. Each of the camshoes has its leading and trailing ends turned outward slightly to formrounded edges which provide for smooth engagement and release of thedoor 88 and hinge 92'as they pass under the cams. Cam 94 holds door 88closed until it reaches opening 96, at which point the'door is releasedand drops downwardly to discharge any material within chamber 84 throughopening 91. The material discharged through opening 91 drops-throughopening 96 into a suitable receptacle or conveyor (not shown), by whichit is removed' from the premises'for disposal. The shorter cam shoe 95engages and closes the door 88 as the drum continues to turn,and-holds-the door firmly shut until it reaches a point where gravitytakes over and holds the door down against its seat. I

The gases produced by thepyrolysis of the combustible material, and bythe combustion process within the drum, are sucked out throughan opening96 in end plate 56 and through an exhaust duct and scrubber 98, by ablower 100 driven by a motor 102. From the blower, the gases aredischarged through an exhaust duct 104 to a condenser (not shown), forfurther processing. The amount of suction created by the blower 100 iscontrolled by a slide valve 106, which may be.v manually controlled ormotorized. The exhaust duct and scrubber 98 has water spray nozzles 108protruding through the walls thereof at angularly spaced and,longitudinally spaced intervals, and thesenozzles are connected fto awater supply pipe 110; Exhaust gases drawn off through duct 98 passthrough a fine spray of water and are cooled thereby. At the same time,condensible tars entrained in the gas stream are condensed out, andthese are recovered from the waste water.

The mode of operation of the invention is more or less as follows: Trashfed into the hopper 32 drops by gravity into the entrance end 14 of thedrum, where it is advanced continuously to the pyrolyzing section 18through the transfer compartment 48, while doors 44 and 52 open andclose in alternating sequence. At all times during the transferoperation, one or the other of doors 44, 52 is closed, so that there isno time during the rotation of the drum when both doors are open. Thesame is true of the discharge of non-combustible material throughdischarge chambers 74 and of char through discharge chamber 84. In bothcases, one of the exit doors is always closed'when the other is open, sothat at no time is the interior of the drum open to the atmosphere.

The blower 62 runs continually feeding air to the two burner nozzles 58.Natural gas or other fuel is supplied to the burners 58 only during thepreheat stage, when the drum and its contents are being brought up to aninitial operating temperature of approximately 1200 F. The burners arethermostatically controlled to maintain the predetermined operatingtemperature. As the material heats up, gases are formed by thedestructive distillation of the carbonaceous material in the drum, andeventually 'purge the system of all the initial atmosphere inside thedrum. At this time, the fuel valve 68 is shut off, and air valve 70 isset to admit air in an amount suflicient to provide oxygen for thecombustion of part of the combustible gases inside the drum. Thatportion of the combustible gas which is mixed with air ignites, and theflame will sustain itself as long as the necessary amount of oxygen issupplied. The air supply is controlled by valve 70, and the latter isregulated by a temperature sensor (not shown), which increases ordecreases the amount of air, as required, to hold the operatingtemperature to approximately 1400 F. It has been found by experiencethat only about 15% of the total gas generated by pyrolysis is needed tomake up the heat losses of the system and to sustain pyrolysis. Theexcess gas, together with the combustion gases, are drawn off by theexhaust blower to a condenser for further processing.

The apparatus shown and described herein is capable of acceptingmunicipal or industrial trash, and without grinding or otherpreparation, of reducing the combustible portion thereof into charcoaland gas. The greatest portron of combustible components such as Wood,and woodderived by-products, including paper, cardboard, pressed wood,etc., is reduced to approximately 20% of its original mass. Plastics,paints, rubber, and other organic materials reduce to approximately 10%of their original mass. Noncombustible materials, such as metal parts,become stripped of their coatings of oil or paint, and become morevaluable when sold for scrap metal. Other inert materialssuch as rocksand chunks of concrete help in the crushing and disintegration of thecombustible material.

One advantageous feature of the invention is that the drum may befabricated of steel and lined internally with refractories. The flame isentirely containedwithin the drum, and its heat impinges only on therefractory and the material being'processed. The refractory becomes aheat barrier so that the steel shell may be'maintained at a temperaturebelow 1000 F., while allowing the internal temperatureto rise as high as3000 F:,"'if necessary. This factor of'increased'operating temperaturemakes'possible a material reduction in capital equipment costs, as trashcan be processed from three'to four times-"faster than in externallyfired retorts. Moreover, transmiss'ion of heat from the flame to thematerial being processed is .transferred through the gaseous atmospherecontained within the drum, as opposed to being transmitted by conductionthrough the walls of a steel drum.-

While we have shown and described in considerable detail what we believeto be the preferred embodiment of the invention, it will beunderstood'by those skilled in the 7 art that the invention is not limited to suchdetails, but might take entirely different forms within the scope of theclaims that follow.

What is claimed is:

1. An apparatus for decomposition of trash by heating the trash tobecome a charred residue of relatively reduced bulk utilizingcombustible gas created by destructive distillation of carbonaceousmaterial in the trash as a heating medium, the apparatus comprising:

a retort having an enclosed, hollow interior sealed from the atmosphereoutside the retort and adapted to receive the trash and to contain theresidue,

means for providing access to the interior of said retort to enabletrash to be delivered thereto and the residue be removed therefrom,

means for sealing said access providing means for preventingcommunication through said means at any time between the interior of theretort and the atmosphere outside of said retort,

means for sensing the temperature inside the retort,

auxiliary means connected with the interior of said retort for raisingthe temperature therein to the level necessary for destructivedistillation of the carbonaceous material during an initial start-upperiod of operation,

means for terminating operation of said auxiliary means when thetemperature sensed by said temperature sensing means reaches thetemperature necessary for destructive distillation of the carbonaceousmaterial in the trash, thereby creating combustible gas,

means for admitting a controlled flow of non-combustibleoxygen-containing gas to the interior of said retort in an amountsufiicient to permit complete combustion of only a portion of saidcombustible gas as it is created by the destructive distillation oftrash within said retort,

means connected with said admitting means for regulating the fiow ofnon-combustible oxygen-containing gas in response to the temperaturesensing means to maintain the temperature within the interior of saidretort between a lower level necessary to maintain destructivedistillation of trash and a predetermined upper level, the combustion ofthe portion of the combustible gas being sufficient to maintain thetemperature of the interior of said retort above the level necessary forsaid destructive distillation without heat or fuel from any othersource, said admitting means providing substantially the only inlet foroxygencontaining gas into the interior of the retort after terminatingoperation of the auxiliary heating means, and an outlet for escape ofcombusted and uncombusted gases from the interior of said retort.

2. An apparatus as defined in claim 1 wherein said auxiliary means forraising the temperature during startup includes a burner incommunication with the interior of said retort and connected to anexternal supply of combustible fuel, said burner heating the interior ofsaid retort until the temperature necessary for destructive distillationis reached.

3. An apparatus as defined in claim 1 in which said means for providingaccess to the interior of said retort includes trash inlet meansconnected with said retort for admitting a fiow of the trash to theinterior of said retort and residue outlet means connected with saidretort for outflow of charred residue from the interior of said retort,and I said means for sealing the interior of said retort includes inletseal means enabling passage of trash through said trash inlet meanswithout placing the interior in communication with the outsideatmosphere and outlet seal means enabling passage of residue throughsaid residue outlet means without plac- 8 ing the interior incommunication with the outside atmosphere.

4. An apparatus as defined in claim 1 wherein said retort is providedwith a refractory lining about its inner surfaces defining the interior,said lining providing thermal insulation between the interior and theremainder of said retort.

5. An apparatus as defined in claim 4 wherein said retort comprises acylindrical drum mounted for rotation about an approximately horizontalaxis, said inlet and outlet means being connected with opposite axialends of said drum, the apparatus further including means for rotatingsaid drum about the horizontal axis and a spiral flight within said drumfor moving the contents thereof toward said outlet means as said drum isrotated.

6. An apparatus as defined in claim 1 further including means connectedwith said outlet for condensing at least a portion of the gases leavingsaid outlet.

7. An apparatus as defined in claim 1 further including an exhaustblower connected with said outlet for drawing the combusted anduncombusted gases through said outlet from the interior of said retort.

8. An apparatus as defined in claim 3 wherein said retort extendslongitudinally, with said outlet for gases being positioned at onelongitudinal end of said retort, said burner being positioned internallyof said retort adjacent the same longitudinal end thereof as said outletfor gases. as a;

9. Apparatus for the pyrolytic decomposition of trash, comprising, incombination:

an elongated drum supported for rotation about an approximatelyhorizontal axis, said drum having an entrance end, an exit end, and amid-section between said ends;

means for driving said drum at a relatively slow rate of rotation;loading means at the entrance of said drum for introducing trash intothe interior of the drum while at all times excluding atmospheric airfrom entering that end of the drum through said loading means;

discharging means at the exit end of said drum for removing the residueof the trash from the interior of the drum while at all times excludingatmospheric air from entering that end of the drum through saiddischarging means;

at least one burner projecting into the interior of said drum at theexit end thereof, said burner being connected to a source of fuel;

means for supplying air to said burner to support combustion of saidfuel, the interior of said drum being sealed against any substantialinflow of atmospheric air except that supplied to said burner;

valve means for admitting fuel to the burner during an initial start-upperiod for raising the temperature inside the drum to a predeterminedlevel sufiicient to cause destructive distillation of the carbonaceousmaterial in the trash, with resultant production of combustible gas andfor shutting otf the source of fuel to said burner when the interior ofsaid drum and its contents have reached the predetermined temperatureand said interior has become filled with combustible gas produced bydestructive distillation of the carbonaceous material in said trash;means for regulating the supply of air to the interio of said drum toprovide no more than enough oxygen to support combustion of the fuelduring operation of the burner, whereby an oxygen-deficient atmosphereat elevated temperature is obtained in the interior of the drum, and toprovide oxygen for the combustion of only part of the combustible gasgenerated by the decomposition of trash within said drum after said fuelsupply tosaid burner has been shut off, so as to supply heat forsustaining the pyrolytic decomposition of the trash without additionalfuel; and

means for exhausting the combustion products resulting from the burningof said gas.

10. Apparatus as in claim 12, wherein said loading means at the entranceend of said drum for introducing trash into the interior of the drumwhile providing a barrier between the interior and the atmospherecomprises:

first and second bulkheads disposed adjacent one another and spanningthe entire interior of said drum, said bulkheads defining between them aclosed transfer compartment;

each of said bulkheads having an opening therein closed by a door, saidopenings being spaced apart angularly from one another about the axis ofrotation of the drum;

said doors being movably mounted with respect to the bulkhead relatedthereto to open in sequence when said drum is rotated so that trashloaded into said entrance end of the drum passes through the open doorin said first bulkhead and into said transfer compartment while the doorin said second bulkhead is closed, and then as the drum continues torevolve, said door and said first bulkhead closes and said door in saidsecond bulkhead opens, allowing trash in said transfer compartment topass through to said intermediate section of the drum where pyrolyticdecomposition takes place.

11. Apparatus as defined in claim 10, wherein said bulkheads areinclined in opposite directions to one another, said first bulkheadhaving its opening adjacent the edge nearest said entrance end of saiddrum, and said second bulkhead having its opening diametrically oppositefrom the opening in said first bulkhead;

each of said openings having a door hinged to the edge against the wallfor drum, said doors being located on the side of the bulkhead facingtowards said midsection; each of said doors being operable to open bygravity when its hinged portion is at the bottom of the drum and toclose by gravity when its hinged portion is at the top of the drum,whereby said doors open and close in alternate sequence as said drumrevolves.

12. A method for decomposing trash by heating it to become a charredresidue of relatively reduced bulk, utilizing combustible gas created bydestructive distillation of carbonaceous material in the trash as aheating medium, the method comprising the steps of:

holding trash in the interior of a retort at a temperature sufficient tocause distillation of combustible gas from carbonaceous material in thetrash while maintaining the interior of the retort closed againstcommunication with atmospheric air;

burning the combustible gas within the interior of the retort tomaintain the temperature at a level sulficient for continuing thedestructive distillation of the carbonaceous material in the trashthereby creating additional combustible gas;

admitting a controlled flow of only non-combustible oxygen-containinggas to the interior of the retort to sustain combustion of only aportion of the combustible gas generated by the destructive distillationof the trash within the interior of the retort, the combustion of theportion of the combustible gas being sufficient to maintain thetemperature of the interior of the retort above the level necessary fordestructive distillation, and sensing the temperature within theinterior of the retort,

regulating the flow of oxygen-containing gas admitted to the interior ofthe retort in response to the sensed temperature to control thetemperature between a lower level necessary to sustain destructivedistillation of the trash and a predetermined upper level, and

permitting outflow of combusted and uncombusted gases from the chamber.

13. A method as defined in claim 12 wherein there is an initial start-upperiod during which the temperature within the interior of the retort israised from a lower temperature to the level necesary to causedestructive distillation of the carbonaceous material Within the trash,the method including an initial step of:

burning an auxiliary fuel charge within the interior of the retortduring the start-up period until the temperature is raised to the levelnecessary for destructive distillation.

14. A method as defined in claim 12 wherein there is an initial start-upperiod during which the temperature within the interior of the retort israised from a lower temperature to the level necessary to causedestructive distillation of the carbonaceous material in the trash, themethod including the steps of:

burning auxiliary fuel supplied from an external source to a burnerpositioned within the interior of the retort to raise the temperature ofthe interior of the retort; and

terminating the supply of auxiliary fuel to the burner when the sensedtemperature in the interior of the retort reaches the level necessaryfor destructive distillation.

15. A method as defined in claim 12 including the initial step ofprotecting the retort against the high temperatures generated Within itsinterior by lining inner surfaces of the retort defining the interiorthereof with refractory material.

16. A method as defined in claim 12 wherein the retort is configured asa drum mounted for rotation about an approximately horizontal axis withtrash entering the drum at one axial end of the drum and leaving as acharred residue at the other axial end, the method including the stepsof rotating the drum about the horizontal axis and moving the trashwithin the drum towards the outlet end as the drum rotates.

References Cited UNITED STATES PATENTS 3,705,086 12/1972 Schmalfeld201-36 3,306,237 2/1967 Ransom 432-72 X 2,813,822 11/1957 Collier 201251,518,938 12/1924 Nielsen 202131 X NORMAN YUDKOFF, Primary Examiner D.EDWARDS, Assistant Examiner US. Cl. X.R.

